Sheet feeding apparatus

ABSTRACT

A vacuum feeder includes an extensible chamber which can be moved from an extended position to a contracted position in response to a reduction of pressure within the chamber. The movable section of the chamber includes an aperture which is positioned adjacent a sheet at a first station so that withdrawal of air from the chamber sucks the sheet over the aperture. Further withdrawal of air therefore produces a vacuum or partial vacuum within the chamber retaining the sheet over the aperture while simultaneously causing the chamber to contract from its extended position. The contraction results in a transferal of the retained sheet from the first station to a second station.

United States Patent Gray et al. Oct. 9, 1973 [54] SHEET FEEDING APPARATUS 2,2l5,458 9/1940 Backhouse 271/27 [75] Inventors: Colin Gray; Anthony Robert Burge,

both f w f d England Primary Examiner-R1chard E. Aegerter Attorney-Kemon, Palmer & Estabrook [73] Ass1gnee: Crosfield Buslness Machlnes Limited, Watford Hertfordshire, England [5 7] ABSTRACT [22] Filed: June 7, 1971 A vacuum feeder includes an extensible chamber 1 which can be moved from an extended position to a [21] Appl 5 contracted position in response to a reduction of pressure within the'chamber. The movable section of the [30] Foreign Application Priority Data chamber includes an aperture which is positioned adme 9 1970 Great Britain 27,902 70 J'acem Sheet at first swim that wilhdrawal of air from the chamber sucks the sheet over the aper- 52 us. 01. 271/27, 271/29 Further Withdrawal air therefore Produces a 51 1111. C1 B65h 3/08 Vacuum 0r Partial vacuum Within the chamber retain- [58] Field of Search 271/26 27 74 ing the Sheet Over the apermfe While Simultaneously causing the chamber to contract from its extended po [56] References Cited sition. The contraction results in a transferal of the re- UNITED STATES PATENTS tained sheet from the first station to a second station.

3,039,767 6/1962 Staines 271/26 R 14 Claims, 5 Drawing Figures PATENTEUBBT 91m 3,764,133 SHEET 10F 3 lnvenlors COL) snn han BM:

Wtlorney SHEET FEEDING APPARATUS mally incorporate an independent power drive to move the transporting surface, and some form of valving for applying and releasing suction at fixed intervals so that the sheets are picked up from the first station and released at the second station. The transporting surface may comprise a suction cup at the end of a swinging arm, or, more recently, the peripheral surface of a rotary drum.

In accordance with the present invention sheet feeding apparatus includes an extensible chamber having a section movable from an extended position to a contracted position in response to a reduction of pressure within the chamber, and the said section includes an aperture positioned such that, with the chamber extended and the aperture placed adjacent a sheet at the first station, withdrawal of air from the chamber draws the sheet over the aperture and further withdrawal of air produces a vacuum or partial vacuum within the chamber retaining the sheet over the aperture while simultaneously causing the chamber to contract from its extended position, the contraction resulting in a transferal of the retained sheet from the first station to a second station.

In a preferred embodiment of the invention the chamber is automatically vented in response to the movement of the chamber into its contracted position such that, in operation, the sheet is released from the movable section as the section movesinto the second station. The apparatus also preferably includes means for urging the movable section toward its extended position such that the section is automatically returned to the first station after the chamber has been vented.

The sheets themselves therefore control the valving of the system and an important advantage of the invention is that an independent drive for the transporting surface is not required.

Some examples of the invention will now be described with reference to the accompanying drawings in which:

FIG. I is a side elevational view of a telescopic sheet feeding apparatus,

FIG. 2 is a side elevational view ofa reciprocating rotary sheet feeding apparatus FIG. 3 is a development of the sector surface of the chamber segment shown in FIG. 2,

FIG. 4 is a right-hand end view of the apparatus shown in FIG. 2 and FIG. 5 is a side elevational view of a continuous rotary sheet feeding apparatus.

Referring first to FIG. 1 a telescopic chamber includes a fixed inner tube 1 and an extensible sleeve 3. The chamber is pivotally mounted on a pivotal bearing 2 such that it can swing from the position shown in FIG. 1 to a substantially vertical position.

The pivoted end of the chamber is also connected to a vacuum source (not shown) and an adjustable valve 15 controls the withdrawal of air from the chamber to the vacuum source.

The chamber is held in the position shown in the drawing with the sleeve extended by a linking arm 8 and clock spring 16. However, when the chamber is connected to the vacuum source, the forwardmost sheet in the stack of sheets 17 at a first station is sucked over the aperture at the end of the sleeve 3, and the resulting drop in internal pressure causes the sleeve to slide up the inner tube. Since the linking arm 8 is pivotally connected to a lug 10 of the sleeve 3, this upward movement of the sleeve rotates the linking arm 8 clock-' wise to wind the spring 16 and simultaneously pulls the chamber into the vertical position such that the sheet over the end of the tube 3 is transferred to a second station.

In the extended position of the sleeve 3, the port 6 in the sleeve and the port 5 in the inner tube 1 are out of alignment with one another, but as the sleeve is contracted over the tube the ports move into alignment so that the chamber is vented to the atmosphere. This occurs when the chamber is substantially vertical so that as the retained sheet over the end of the sleeve 3 strikes the stop plate 19 it will be released and fall onto the stack of sheets 18. A stripper plate 20 assists the peeling of the sheet from the end of the sleeve.

Alternatively, the sheet may be fed into pinch rolls 21 (shown dotted) and, in this case, only a limited lateral movement of the chamber is required because the pinch rolls can continue pulling the sheet clear of the stack 17. This, however, requires that the chamber is held stationary and this can be achieved by controlling the degree of venting to balance the force exerted by the linking arm. The degree of venting would be sufficient to hold the sheet lightly over the end of the sleeve and full venting would then occur when the pinch rolls had dragged the sheet clear of the end of the sleeve.

For a large pile of sheets it is important that the extension of the sleeve is reasonably consistent for each sheet'and this could be achieved by an additional arm on the sleeve operating a ratchet or toothed wheel arrangement whenever the sleeve is extended beyond a particular limit, the resulting movement being used to raise the plate on which the sheets are stacked.

The device is also particularly useful where it is required to feed sheets from the bottom of a stack supported by rails. Since each sheet is withdrawn from the bottom of the stack substantially at right-angles to the plane of the sheets, friction between the sheet being removed and the next sheet is much less than in an arrangement where each sheet is slid out from the stack. A handle 22 enables the sleeve 3 to be lifted in order to load the sheets 17.

Referring next to FIGS. 2 to 4, the chamber for transporting the documents is now formed as a moving sector or segment 30 of a cylinder. The circumferential surface 31 of the sector is shown in detail in FIG. 3. The moving sector can pivot about a central bearing 32 and air can be withdrawn from the sector along the air passage 33 which is connected to a vacuum source (not shown) at the end of a duct 34. The moving sector includes an end plate 35 and two side walls 36 (FIG. 4). A fixed vane 37 attached to the casing 38 forms a loose fit at the other end of the chamber so that when the vacuum source is connected to the air passage 33 air is withdrawn from the chamber and a sheet from the stack 39 is sucked over the apertures 40 in the circumferential surface, the resulting reduction in pressure in the movable sector causing the end plate 35 and side walls 36 to rotate about the bearing 32 past the fixed vane 37. This movement continues until a depression 41 provided in at least one of the side walls 36 reaches the vane 37 when an air release path will be formed around the vane thus venting the chamber. This will occur as the retained sheet on the circumferential surface reaches the stack 42 at the second station. The peeling of the sheet from the circumferential surface is assisted by the stripper 43.

As can be seen from FIG. 3, the apertures 40 in fact comprise vacuum grooves 40a which hold the document against the circumferential surface of the mov able sector. The vacuum force from the four grooves is greater than the retaining force which is present at a port 44 in the casing 38, the latter force holding the bottom edge of the forwardmost sheet in the stack 39 until the top of the sheet is gripped by the vacuum grooves. This helps to smooth the sheet around the circumferential surface.

As soon as the chamber has been vented, a clock spring 45 (FIG. 4) will rotate the movable sector back to its original position shown in FIG. 2. On this return stroke, air is trapped in a cushioning chamber 46 formed between the endplate 35, a right-angled portion of casing 38 and an extension 47 of the movable sector.

FIG. illustrates a full rotary system in which two extensible chambers are formed in the annulus between a hollow-walled cylinder 50 and an eccentric, inner fixed circular cam 51. The hollow cylinder rotates about a drum cantilever bearing 52, and a vacuum source is connected to a port 53 in the inner cam. In the position shown in the figure, connection of the vacuum source withdraws air from the chamber 54 so that a sheet from the stack 55 is sucked over the aperture 56. The resulting reduction in pressure causes the end wall formed by a sliding vane 59a to be drawn toward the vacuum and the cylinder is therefore rotated anticlockwise to transfer the retained sheet to the stack 57.

As the cylinder rotates the volume of the chamber 54 contracts while that of chamber 58 expands due to the eccentricity of the cam. As the vane 59a reaches the vacuum port the retained sheet is peeled away from the peripheral surface of the cylinder to vent the chamber 54. During this contraction of chamber 54, the vane 59a has moved back into its slot 60 and a linked vane 59b diametrically opposed to the vane 59a has therefore been drawn out of its corresponding slot into the position occupied by the vane 59a in the drawing. Thus, as chamber 54 is vented, a second aperture 61 adjacent the vane 59b moves into the first station, and the vacuum source will then suck the next sheet across aperture 61 and evacuate chamber 58. The process is therefore repeated continuously until all the sheets have been transferred to the second station.

One alternative to the sliding vanes is to pivotally mount the vanes on the cylinder wall. The vanes would then preferably have a radius of curvature less than the radius of curvature of the cam and would be resiliently biased into contract with the cam. Thus, as each vane descends towards its lowermost position (when it will be lying substantially flat) the tip of the vane remains in contact with the cam.

In all the described embodiments it is not essential to obtain a complete vacuum to bring about the required contraction of the chamber, and hence the sealing of the chamber during its contraction is not critical.

We claim:

1. Sheet feeding apparatus including;

a. an extensible chamber having a section for engaging a sheet to be transferred from a first station to a second station, said section movable from a first position to a second position in response to a reduction of pressure within said chamber,

b. a port opening into said chamber through which air may be withdrawn from said chamber,

c. an aperture in said section to overlie a sheet at said first station when said section is in said first position whereby withdrawal of air through said port firstly draws said sheet over said aperture and subsequently reduces the pressure within said chamber to move the said section from its first position to its second position, and

d. means responsive to the resulting contraction of the chamber for imparting a translational motion to the sheet such that the sheet is advanced along a fixed path from said first station to said second station.

2. Apparatus according to claim 1 including means responsive to the movement of said section into its second position for venting said chamber whereby, in operation the sheet is released from the said section as the sheet moves into said second station.

3. Apparatus according to claim 2 further including means for urging said section toward its first position such that said section is automatically returned to the first station after the chamber has been vented.

4. Apparatus according to claim 1 in which said moving section comprises an extensible sleeve fitted over a fixed inner tube, the apparatus further comprising a fixed bearing about which said tube is rotatable, and said aperture being formed in the protruding end of the sleeve.

5. Apparatus according to claim 4 in which the sleeve and the tube each include a venting port, the two ports being aligned with one another only when the sleeve is in its contracted position.

6. Apparatus according to claim 4 further including a link having one end pivotally connected to the sleeve such that, with the other end pivotally connected to a fixed point, rotation of said link about the fixed point in response to a contraction of the sleeve produces a lateral movement of the sleeve toward the second station.

7. Apparatus according to claim 1 in which said chamber includes a curved peripheral top surface, side walls and a pair of end walls, the peripheral top surface, the side walls and a first of the end walls being pivotally mounted for rotation about a fixed bearing, the second end wall of the chamber being fixed such that the volume of the chamber may be contracted by rotating the first end wall toward the second end wall.

8. Apparatus according to claim 7 in which the side walls are contoured such that a venting port is formed between the second end wall and at least one of the side walls as soon as the peripheral surface has rotated through the angle required to transfer a sheet from the first station to the second station.

9. Apparatus according to claim 7 in which the aperture is formed in the said peripheral surface and is positioned such that the leading portion of a sheet at the first station is drawn across the aperture when air is withdrawn from the chamber, the apparatus further including means for holding the trailing portion of the said sheet against the peripheral surface with a force substantially less than the vacuum force retaining the said leading portion over the aperture.

10. Apparatus according to claim 1 further comprising a rotatably mounted cylinder and an eccentric fixed cam within the cylinder, the extensible chamber comprising a portion of the annulus between the outer cylinder and the inner fixed cam.

l 1. Apparatus according to claim in which the end walls of the chamber comprise a pair off diametrically opposed linked vanes slidably mounted in slots formed in the wall of the cylinder, the said aperture being formed through the wall of the cylinder adjacent one of the vanes and the inner cam including said port opening into the said annulus for connection to a vacuum source.

12. Apparatus according to claim 11 including a second aperture through the wall of the cylinder diametrically opposed to the first aperture such that the said vanes divide the annulus into two symmetrical extensible chambers and, with the port opening into the first chamber, rotation of the cylinder to transfer a sheet retained over the first aperture from the first station to a second station simultaneously moves the second aperture into the first station as the trailing end wall of the first chamber moves across the said port to permit withdrawal of air from the second chamber.

13. Apparatus according to claim 10 in which the end walls of the chamber comprise a pair of diametrically opposed vanes pivotally mounted on the inner wall of the cylinder and resiliently biased toward the inner cam. I

14. Apparatus according to claim 13 in which the vanes are curved with a radius of curvature less than the radius of curvature of the cam. 

1. Sheet feeding apparatus including; a. an extensible chamber having a section for engaging a sheet to be transferred from a first station to a second station, said section movable from a first position to a second position in response to a reduction of pressure within said chamber, b. a port opening into said chamber through which air may be withdrawn from said chamber, c. an aperture in said section to overlie a sheet at said first station when said section is in said first position whereby withdrawal of air through said port firstly draws said sheet Over said aperture and subsequently reduces the pressure within said chamber to move the said section from its first position to its second position, and d. means responsive to the resulting contraction of the chamber for imparting a translational motion to the sheet such that the sheet is advanced along a fixed path from said first station to said second station.
 2. Apparatus according to claim 1 including means responsive to the movement of said section into its second position for venting said chamber whereby, in operation, the sheet is released from the said section as the sheet moves into said second station.
 3. Apparatus according to claim 2 further including means for urging said section toward its first position such that said section is automatically returned to the first station after the chamber has been vented.
 4. Apparatus according to claim 1 in which said moving section comprises an extensible sleeve fitted over a fixed inner tube, the apparatus further comprising a fixed bearing about which said tube is rotatable, and said aperture being formed in the protruding end of the sleeve.
 5. Apparatus according to claim 4 in which the sleeve and the tube each include a venting port, the two ports being aligned with one another only when the sleeve is in its contracted position.
 6. Apparatus according to claim 4 further including a link having one end pivotally connected to the sleeve such that, with the other end pivotally connected to a fixed point, rotation of said link about the fixed point in response to a contraction of the sleeve produces a lateral movement of the sleeve toward the second station.
 7. Apparatus according to claim 1 in which said chamber includes a curved peripheral top surface, side walls and a pair of end walls, the peripheral top surface, the side walls and a first of the end walls being pivotally mounted for rotation about a fixed bearing, the second end wall of the chamber being fixed such that the volume of the chamber may be contracted by rotating the first end wall toward the second end wall.
 8. Apparatus according to claim 7 in which the side walls are contoured such that a venting port is formed between the second end wall and at least one of the side walls as soon as the peripheral surface has rotated through the angle required to transfer a sheet from the first station to the second station.
 9. Apparatus according to claim 7 in which the aperture is formed in the said peripheral surface and is positioned such that the leading portion of a sheet at the first station is drawn across the aperture when air is withdrawn from the chamber, the apparatus further including means for holding the trailing portion of the said sheet against the peripheral surface with a force substantially less than the vacuum force retaining the said leading portion over the aperture.
 10. Apparatus according to claim 1 further comprising a rotatably mounted cylinder and an eccentric fixed cam within the cylinder, the extensible chamber comprising a portion of the annulus between the outer cylinder and the inner fixed cam.
 11. Apparatus according to claim 10 in which the end walls of the chamber comprise a pair of diametrically opposed linked vanes slidably mounted in slots formed in the wall of the cylinder, the said aperture being formed through the wall of the cylinder adjacent one of the vanes and the inner cam including said port opening into the said annulus for connection to a vacuum source.
 12. Apparatus according to claim 11 including a second aperture through the wall of the cylinder diametrically opposed to the first aperture such that the said vanes divide the annulus into two symmetrical extensible chambers and, with the port opening into the first chamber, rotation of the cylinder to transfer a sheet retained over the first aperture from the first station to a second station simultaneously moves the second aperture into the first station as the trailing end wall of the first chamber moves across the said port to Permit withdrawal of air from the second chamber.
 13. Apparatus according to claim 10 in which the end walls of the chamber comprise a pair of diametrically opposed vanes pivotally mounted on the inner wall of the cylinder and resiliently biased toward the inner cam.
 14. Apparatus according to claim 13 in which the vanes are curved with a radius of curvature less than the radius of curvature of the cam. 